Summary & Overview
CPT 83930: Blood Osmolality Measurement, Serum
CPT code 83930 represents a laboratory procedure that measures blood osmolality, most commonly on a serum sample. This clinical chemistry test provides a quantitative assessment of dissolved particles in blood and is used to evaluate fluid balance, electrolyte disorders, and the osmotic contribution of solutes such as sodium, glucose, and urea. Nationally, osmolality testing is a routine diagnostic tool in inpatient and outpatient settings for patients with suspected dehydration, hyponatremia, hypernatremia, altered mental status, or suspected toxic ingestions.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context for ordering the test, typical sites of service, and the role of 83930 in diagnostic workflows. The publication summarizes billing and coding considerations, common modifiers, and where Data not available in the input prevents more granular payer-specific reimbursement benchmarks. It also highlights related clinical scenarios in which blood osmolality results influence diagnosis and management decisions.
This content is intended for a national audience of clinicians, laboratory managers, and revenue cycle professionals seeking a concise reference to the clinical purpose and billing context of CPT code 83930.
Billing Code Overview
CPT code 83930 describes a laboratory measurement of blood osmolality, typically performed on a serum sample. Osmolality quantifies the number of dissolved particles in a solution and is used to evaluate a patient’s fluid and electrolyte balance. The test detects changes that affect the freezing and boiling points of the sample and helps assess conditions such as dehydration, overhydration, and disturbances in sodium, glucose, or urea concentrations.
Service Type: Clinical laboratory diagnostic test
Typical Site of Service: Clinical laboratory or hospital laboratory
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult presenting to the emergency department or inpatient unit with altered mental status, suspected electrolyte disturbance, suspected volume depletion, or conditions that may alter serum osmolality (for example, suspected poisoning with toxic alcohols, severe hyperglycemia, or severe hyponatremia). A clinician orders a serum osmolality test when measured serum sodium, glucose, or BUN values do not fully explain the patient’s clinical picture or when evaluation of osmotic gap is needed.
The clinical workflow: a phlebotomist obtains a serum sample, which is labeled and sent to the clinical laboratory. The laboratory technologist or automated chemistry analyzer performs the 83930 assay to measure serum osmolality, documents the numeric result in the laboratory information system, and transmits the result to the ordering provider. Results are interpreted in context with concurrent serum electrolytes, glucose, and BUN to assess for osmotic gap, dehydration, or toxic alcohol ingestion. Typical sites of service include hospital inpatient wards, emergency departments, and outpatient hospital-based laboratories or reference labs.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the professional/interpretive component of the laboratory test if applicable (rare for automated chemistry tests). |